RunRyder RC
 10  Topic Subscribe
WATCH
 3 pages [ <<    <    ( 1 )     2      3     NEXT    >> ] 5631 views
Scorpion Power Scorpion Power
HelicopterGasser Model RC HelicoptersOther › DIAPHRAGM Maintenance...
03-16-2009 09:52 PM  8 years agoPost 1
iskoos

rrKey Veteran

Orlando, FL

My Posts: All  Forum  Topic

1.How often does it need to be replaced?
2.Is it just the diaphragm that goes bad in the carb?

3.And is that true that using high octane fuel protects the diaphragm?(sounds like a myth but wanted to confirm)

My PUH 231 on my Spectra-G was doing terrible lately. Whatever I did wasn't helping at all. A friend of mine pointed out the diaphragm. After replacing it, the engine was whole lot better. I can't say it is perfect yet but I can at least hover the ship. Before, it was impossiple to get her into hover. It was leaning out and quiting at every possible needle setting.
Anyways, top 3 questions please...

Thanks

PM  EMAIL  GALLERY  Attn:RR  Quote
03-17-2009 01:48 AM  8 years agoPost 2
bosshoss

rrVeteran

Chicago, IL

My Posts: All  Forum  Topic

I replace the diaphragm went it looks wrinkled up.

No, other parts can go wrong, pump membrane, screen plugged, metering needle(what some might call the "float", and ther eis one part in the carb that you CANNOT replace, it is the main "jet".

Not really a typical "jete" , but an orifice with a ball and spring that moves with vacuum and acts as a main jet.

No myths allowed, yes certain fuels attack the rubber more than otheras. With as many additives as there are now, it can vary from region to region.

Why Hover a Yak, when a Heli does it better?

PM  EMAIL  HOMEPAGE  Attn:RR  Quote
03-17-2009 03:08 PM  8 years agoPost 3
iskoos

rrKey Veteran

Orlando, FL

My Posts: All  Forum  Topic

I bought a kit and replaced all the parts including the gaskets, needle etc. I know it won't make any difference but I figured that it won't hurt. The only part I found defective was the diaphragm. It was not flat anymore. Not wrinkled but like somehow got strecthed.
However, the Walbro rebuild kit I bought used a different kind (black as opposed to tan color)of material for the diaphragm. I first tought they gave me the wrong kit and I went back to replace it. Guy checked out the catalog again and insisted that it was the right kit. He said it was the same diaphragm but the company used slightly different material. He assured me that it would do the same thing.
This diaphragm has the same shape and thickness, just the color was different. I am hoping it will do the same job...

So do you guys use regular (87 octane) fuel or higher grade?

PM  EMAIL  GALLERY  Attn:RR  Quote
03-17-2009 03:38 PM  8 years agoPost 4
BLT4FUN

rrNovice

Delphos, OH

My Posts: All  Forum  Topic

I think thats something she should be asking!

Its much easier to ask for forgiveness than permission!!!

PM  EMAIL  GALLERY  Attn:RR  Quote
03-18-2009 01:27 AM  8 years agoPost 5
FloridaHeli

rrVeteran

jacksonville,​florida

My Posts: All  Forum  Topic

iskoos

Can you please advise the part no for the kit and where you got it?

My local lawn mower repair shop only knows part nos. from mowers. Bring in a carburetor and he don't know how to look up the parts.

Thanks for any info you care to share.

This hobby is WAY too expensive!!

PM  EMAIL  GALLERY  Attn:RR  Quote
03-18-2009 02:32 AM  8 years agoPost 6
pphil611

rrApprentice

South Dakota

My Posts: All  Forum  Topic

carb kit

seems like there are four differant materials they use, I have heard they all work about the same. Go to walburo web site.

Spectra-G, MAH, CSM

PM  EMAIL  GALLERY  Attn:RR  Quote
03-18-2009 10:13 AM  8 years agoPost 7
j.8

rrVeteran

Denmark

My Posts: All  Forum  Topic

Hi
My local lawn mower repair shop only knows part nos. from mowers. Bring in a carburetor and he don't know how to look up the parts
Repair kit for a walbro wt carburator is called
K10-WAT
Most small engien shops have them

Regards Bo

PM  EMAIL  GALLERY  Attn:RR  Quote
03-18-2009 12:25 PM  8 years agoPost 8
bosshoss

rrVeteran

Chicago, IL

My Posts: All  Forum  Topic

Wait a minute.

IF you are talking about the PUMP side of the carb, the single screw side, the blue or tan membrane that is in the replacement kit stink.

The Viton rubber membrane that has the pump "flaps" is best, works best and wont get "sticky stuck" (like the oil you use leaves a residue , you don;t fly for a month and the pump flaps "stick" like the blue or tan membrane. The Black membrane's flappys curl up on edge when they fail, but usually last a long time.

THat can only be had from another new carb. Or someone willing to take one apart and give it to you.

Now, if we are talking about the four screw side , the diaprhagm that has a metal button on it, THAT should be black rubber, and I have never seen one that wasn't.

What are we talking about? The Pump side or the metering side?

Are you having tuning problems or Pumping problems?

Why Hover a Yak, when a Heli does it better?

PM  EMAIL  HOMEPAGE  Attn:RR  Quote
03-18-2009 04:07 PM  8 years agoPost 9
iskoos

rrKey Veteran

Orlando, FL

My Posts: All  Forum  Topic

First off, FloridaHeli
I don't have the part # with me but I will let you know when I get home tonight.

Secondly, I was was told that the diaphargm is the thin material on the single screw side. I was thinking it is the one on the other(4 screw) side with the metal button in the center but the guy at the lawn mover shop called that thin part with flappers as diaphragm.
So now I am all confused which one is diaphragm.
But the part that went bad on my carb was the thin material on the single screw side. The original was the tan color and the stuff was out of shape in the middle(meaning it wasn't flat anymore) And the repair kit had the same part but in different color: Black...

Again, I will look up the part number. It was $14 and some change after tax.

PM  EMAIL  GALLERY  Attn:RR  Quote
03-18-2009 04:52 PM  8 years agoPost 10
j.8

rrVeteran

Denmark

My Posts: All  Forum  Topic

Hi
So now I am all confused which one is diaphragm.
Don`t be they are both called diaphragm
just like bosshoss says
What are we talking about? The Pump side or the metering side?
Diaphragm - Assembly Metering
Diaphragm - Fuel Pump
http://wem.walbro.com/walbro/produc...643-1&Series=WT
Regards Bo

PM  EMAIL  GALLERY  Attn:RR  Quote
03-19-2009 01:53 AM  8 years agoPost 11
Tom_in_Cincy

rrNovice

Cincinnati Ohio

My Posts: All  Forum  Topic

I do some repair on Walbro Carbs. The #1 problem with poor running carbs is of course dirt. Make sure your filter screen is clean. When replacing it do not push it all the way down flush with the bottom as it will clog very quickly since the only place the fuel can pass would be right over the tiny drilled hole. Remove the needle valves and the metering valve * don't lose the little spring under the lever. Spray out the carb with carb cleaner from the auto parts store. Use protective goggles when spraying because getting that stuff in your eye is going to hurt. Reassemble the carb with the new gasket kit. You will need to buy a metering gauge. They are inexpensive and you cannot set the carb without one. The metering lever is critical for a good idle. And the gauge measures the lever. Another tool is the pressure gauge with built in pump and it tests for leaks and allows measurement of the spring loaded metering needle . It allows you to test the pop-off pressure of the metering needle (25 - 40 psi) and more importantly tests the fact that it re-seats properly.
When tuning the carb set both needles to about a turn and a half out to start. Always set the low speed needle first. Then the high speed. Typically there are 3 tiny low speed jets that are in progression and one big high speed jet. The throttle baffle exposes each of these 4 jets as you advance the throttle. So you can see the low speed jets are always supplying fuel to the engine even when the throttle is wide open.
The pump diaphragm was made of 3 different materials. The black rubber (pumps the most volume), The tan is Teflon impregnated and is suited for fuels with ethanol in them. It pumps pretty good. Then there is the blue acetate which pumps the least fuel.
Remember the pump diaphragm goes on the carb body then the gasket.
The metering gasket goes against the carb body first then the metering diaphragm. (they are always reversed).
Here is a Ebay link for the lever gauge. http://cgi.ebay.com/OEM-METERING-LE...%3A6%7C294%3A50

This is the pressure tester and the metering level gauge.

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
03-19-2009 04:09 AM  8 years agoPost 12
Billme

rrElite Veteran

MS

My Posts: All  Forum  Topic

Very good post Tom

PM  EMAIL  GALLERY  Attn:RR  Quote
03-19-2009 04:56 AM  8 years agoPost 13
iskoos

rrKey Veteran

Orlando, FL

My Posts: All  Forum  Topic

FloridaHeli

I looked at the part# for you. K20-WAT made by Walbro Engine Management. So it is not some aftermarket stuff.
And my carburator model is WT 643 in case you want to compare.

Tom, I do not have that metering gauge and I don't know how critical to use that. No one ever told me about it so far. But I do have a compression gauge that I can use. Though I plan on using it to measure the engine compression. Do you happen to know what the engine compression specs. for Zenoah 23cc engines?

PM  EMAIL  GALLERY  Attn:RR  Quote
03-19-2009 05:47 AM  8 years agoPost 14
Tom_in_Cincy

rrNovice

Cincinnati Ohio

My Posts: All  Forum  Topic

The WT carb requires the lever height to be .07" below the machined surface of the carb body. You would need the gauge for that as the WT carb is hard to set without. However you could Lay a straight edge across the machined surface of the carb body. The top of the lever ( this is where the center of the metering diaphragm would contact it ) should be .07" lower than the straight edge. Maybe a feeler gauge could be fashioned to fit in there or just a good guess.
Typically on a cylinder compression test gauge I would expect 90 - 140 psi when the engine is turned over with an electric starter. I have only done this test on dual cylinder opposed boxer style engines to see how closely the two jugs matched.

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
03-19-2009 11:29 AM  8 years agoPost 15
j.8

rrVeteran

Denmark

My Posts: All  Forum  Topic

Hi Tom

Incase some ajustment of the metering lever is needed,
how is it done, just by bending it either way ?
I assume the the screw holding it in place needs to be
tight all the time

BTW thanks for some nice info.

Regards Bo

PM  EMAIL  GALLERY  Attn:RR  Quote
03-19-2009 12:36 PM  8 years agoPost 16
Peterr

rrApprentice

Queensland Australia

My Posts: All  Forum  Topic

As j.8 says ,
THANKS for the great info ...

E ,N ,G Whiplash's;Spectra G's;Stratus;E&N Razor,Fury 55;Furion6;TSA 600N, 700N, 700G;; Be

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
03-19-2009 04:49 PM  8 years agoPost 17
Tom_in_Cincy

rrNovice

Cincinnati Ohio

My Posts: All  Forum  Topic

Nice close up of the carb Bo. Yes bend it up or down with a small screw driver. To bend it down you need to hold the metering needle down also. Walbro specifies that the brass metering gauge just slightly moves the lever ( pretty precise haha ) It usually takes a few tries to get it close. The screw in the photo is always kept tight. By the way that small aluminum disk in the lower right covers a fuel passage way that was machined during the manufacture. They are removed for cleaning. A good rebuild kit will contain those plugs. They are not reusable. Removal requires you to pierce them with a sharp awl type device and pry them out (not for the faint of heart ). The new soft aluminum plugs are domed. They are placed in the carb body and struck with a punch to flatten out and seal themselves in.
Have fun
Tom

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
03-19-2009 05:27 PM  8 years agoPost 18
j.8

rrVeteran

Denmark

My Posts: All  Forum  Topic

Hi

Ok I have now checked that the distance betweene the "top"
and the metering lever is ,07 " (1,778 mm)

But I notised that I can push the lever down a little bit
before it actually starts to lift the metering needle, is
that a problem/bad ajustment

Regards Bo

PM  EMAIL  GALLERY  Attn:RR  Quote
03-19-2009 05:38 PM  8 years agoPost 19
AceBird

rrElite Veteran

Utica, NY USA

My Posts: All  Forum  Topic

So you can see the low speed jets are always supplying fuel to the engine even when the throttle is wide open.
This isn’t always the case and more than likely not the case with most carbs. Although the ports are open the barometric pressure (vacuum) goes to near 0 in this region as the butterfly opens. When the butterfly is near the closed position it acts similar to a choke which supplies the vacuum to suck out the fuel from these three holes. On the other hand the high speed jet is increasing in vacuum as the butterfly opens due to the venturi effect. There is truly a transition from the low needle to the high needle and the better that is the more reliable the engine will be when you punch it and let off. It is easy to say your hover is one needle or the other but in reality it is both. Depending on a bunch of different parameters more influence may be the low on one model and the high on another but for sure it is both because you are likely in transition.

You can clearly see that the more power to weight the engine has to lift the more hover will be towards the low needle. In other threads, people are claiming that hover is around 30% open. If this is the case you are well on to the high needle if not totally off the low needle. I can’t imagine any camera ship hovering off the low needle.

Ace
What could be more fun?

PM  EMAIL  GALLERY  Attn:RR  Quote
03-19-2009 06:02 PM  8 years agoPost 20
Tom_in_Cincy

rrNovice

Cincinnati Ohio

My Posts: All  Forum  Topic

Bo your close enough.
Acebird I stand by my statements.

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
WATCH
 3 pages [ <<    <    ( 1 )     2      3     NEXT    >> ] 5631 views
Scorpion Power Scorpion Power
HelicopterGasser Model RC HelicoptersOther › DIAPHRAGM Maintenance...
 Print TOPIC  Make Suggestion 

 10  Topic Subscribe

Friday, November 24 - 8:36 pm - Copyright © 2000-2017 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online